The present invention generally relates to methods of producing magnetic heads, and more particularly to a method of producing a magnetic head which may be used in a cassette tape streaming device.
A cassette tape streaming device records on a cassette tape data which are pre-recorded on a rigid disc so as to function as a back-up system for a rigid disc drive which plays the rigid disc. In a case where the pre-recorded data on the rigid disc are erased erroneously, for example, the cassette tape streaming device is used to transfer the recorded data on a magnetic tape of the cassette tape to the rigid disc drive at a high speed.
In such a cassette tape streaming device, the data are recorded on the magnetic tape according to a group coded recording (GCR) system with a serpentine recording format in which the data are serially recorded on a single continuous track which is formed in a zigzag pattern between the two ends of the magnetic tape.
Since the cassette tape streaming device employs the recording system and the recording format referred to above, a magnetic head of the cassette tape streaming device must have a specific design. That is, a write head and a read head constituting a head pair of a first channel are aligned in a tape transporting direction in which the magnetic tape is transported, and a write head and a read head constituting a head pair of a second channel are aligned in the tape transporting direction. Furthermore, the write head of the first channel and the read head of the second channel are aligned in a direction perpendicular to the tape transporting direction, and the read head of the first channel and the write head of the second channel are aligned in the direction perpendicular to the tape transporting direction.
Such a magnetic head of the cassette tape streaming device must satisfy the following conditions.
(1) Gaps of the write head and the read head of the first channel must be aligned in the tape transporting direction, and gaps of the write head and the read head of the second channel must be aligned in the tape transporting direction.
(2) A distance between the gaps of the write head and the read head of each channel must be accurately set.
(3) A distance between the first and second channels must be accurately set.
(4) The gaps of the write head and the read head which are arranged side by side in the direction perpendicular to the tape transporting direction must be aligned with each other, and the azimuth angle must be accurately equal to 0.degree..
(5) The degree of parallelism of the gaps of the write head and the read head of each channel must be accurately set.
The conditions (1) through (4) must be satisfied mainly for achieving compatibility among cassette tape streaming devices. The condition (5) must be satisfied for improving the recording density.
As will be described later on in the present specification in conjunction with the drawings, one conventional method of producing the magnetic head produces the magnetic head by independently forming a first channel core assembly constituting the write head and the read head of the first channel and a second channel core assembly constituting the write head and the read head of the second channel, connecting the first and second channel core assemblies with a channel shield interposed therebetween, and grinding an upper surface of the connected core assemblies.
On the other hand, another method of producing the magnetic head produces the magnetic head by independently forming a core assembly constituting the write head of the first channel and the read head of the second channel and a core assembly constituting the read head of the first channel and the write head of the second channel, connecting the two core assemblies with a center shield interposed therebetween, and grinding an upper surface of the connected core assemblies.
According to each of the two conventional methods of producing the magnetic head, the accuracy with which the two core assemblies are connected together with the channel shield or the center shield interposed therebetween, the thickness of the channel shield or the center shield, and the degree of parallelism of both surfaces of the channel shield or the center shield directly affect the positional accuracy of the gaps. As a result, according to the conventional methods of producing the magnetic head, there are many primary factors which affect the positional accuracy of the gaps, and there is a problem in that the methods are unsuited for actual mass production of the magnetic head.